Alert archive / Louisiana / Mesoscale Discussions in 2021
Mesoscale Discussion 83
The Storm Prediction Center issued this mesoscale discussion at Feb 14, 2021, 10:53 PM CST for 16 parishes in Louisiana; Wilkinson County, Mississippi; 8 counties in Texas. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 14, 2021, 10:53 PM CST (04:53 UTC)
- Expired
- Feb 15, 2021, 3:00 AM CST
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Winter mixed precipitation
All 25 counties
Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Landry Parish, LA, Vernon Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Wilkinson County, MS, Chambers County, TX, Hardin County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Newton County, TX, Orange County, TX, Tyler County, TX
The radar
The Lake Charles radar (KLCH), 56 km from the middle of the area, began a volume at 04:57 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Lake Charles Mun, LA (KLCH), launched 00:00Z, 4.9 hours before the alert went out and 58 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 2 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 596 m above ground
- 0-6 km bulk shear
- 66 kt
- 0-1 km storm-relative helicity
- 183 m²/s²
- 0-3 km storm-relative helicity
- 304 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
152
ACUS11 KWNS 150454
SWOMCD
SPC MCD 150453
MSZ000-LAZ000-TXZ000-150900-
Mesoscale Discussion 0083
NWS Storm Prediction Center Norman OK
1053 PM CST Sun Feb 14 2021
Areas affected...Parts of southeast Texas into central and southern
Louisiana
Concerning...Winter mixed precipitation
Valid 150453Z - 150900Z
SUMMARY...The development of scattered weak thunderstorm activity
and increasing precipitation rates are expected through 1-3 AM CST
across the Greater Houston Metropolitan area, and the remainder of
southeast Texas into southern and central Louisiana. This probably
will include freezing rain, at least initially, before changing over
to mostly sleet across southeast Texas into southwestern Louisiana.
DISCUSSION...Sub-freezing surface air has reached southeast Texas
through south central Louisiana coastal areas, where lift associated
with lower/mid tropospheric warm advection is contributing to
developing convection and associated precipitation. Models suggest
that modest moistening in the 850-700 mb layer, coupled with
differential thermal advection aloft with the continued gradual
approach of a vigorous mid-level trough, may increasingly contribute
to destabilization supportive of convection capable of producing
lightning through the 07-09Z time frame. As this occurs, there
appears increasing potential for precipitation rates to occasionally
exceed .25 inches per hour.
With at least some further warming above the freezing mark ongoing
in the 850-700 mb layer, this precipitation may initially be in the
form of freezing rain, particularly in the more vigorous convection.
However, model output also indicates that the the sub-freezing
surface-based layer will also gradually deepen across southeastern
Texas into southwestern Louisiana during this time. This is
expected to be accompanied by increasing probabilities for
precipitation to change over to sleet (and probably snow north of a
College Station/Lufkin TX line by 09Z).
..Kerr.. 02/15/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...JAN...LIX...LCH...SHV...HGX...
LAT...LON 29719539 30499510 30899433 31339370 31489133 30799073
29869199 29899347 29429488 29409523 29719539SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 15, 1:08 AM CST | Mesoscale Discussion | SPC | Bienville, Bossier, Caddo, Claiborne, De Soto, Lincoln and 3 more | 6 hr |
| Feb 15, 3:09 AM CST | Mesoscale Discussion | SPC | Ascension, Assumption, East Baton Rouge, East Feliciana, Iberville, Livingston and 9 more | 6 hr |
| Feb 15, 9:28 AM CST | Mesoscale Discussion | SPC | Livingston, Saint Helena, Saint Tammany, Tangipahoa, Washington | 6 hr |
| Feb 15, 5:57 AM CST | Mesoscale Discussion | SPC | Benton, Bolivar, Coahoma, DeSoto, Lafayette, Leflore and 8 more | 6 hr |
| Feb 14, 7:04 PM CST | Mesoscale Discussion | SPC | Bandera, Bastrop, Bell, Bexar, Blanco, Brazos and 35 more | 6 hr |
Nearby
Mesoscale Discussions in Louisiana, 2021Mesoscale Discussions in Texas, 2021Mesoscale Discussions in Mississippi, 2021Every mesoscale discussion in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.